Doesn't sound like the turbo. You may have an issue with fuel delivery, either physical (obstruction or low lift pressure), or a sensor (baro or MAP) is causing the PCM to pull back the fuel. No fuel, no boost, no matter what you do. Without the turbine driving the compressor (either by the WG bypassing, or lack of fuel), the turbo won't whine like you've become accustomed to hearing.

Your vacuum system sounds healthy, with 21/15" indicated. Can't ask for more than that.